Inflatable occupant restraint systems in motor vehicles typically utilize a gas generator or inflator to provide an inflation gas to an airbag, thereby cushioning a vehicle occupant in the event of a crash. A multitude of designs for such systems is known in the art. Generally, a pyrotechnic gas generant material is housed within a relatively robust metallic structure capable of withstanding the temperatures and forces associated with rapid combustion of the material and the associated gas production. Most gas generant materials used in these systems have an extremely rapid burn rate and, accordingly, it is often desirable to control the rate at which inflation gas is ejected from the inflator body. Rather than an extremely rapid output of hot gas, it is in some systems desirable to actually slow the burn rate of the gas generant material, or attenuate its ejection from the inflator body. Various filters, heat sinks and similar items are used in inflator systems to lower the temperature of the inflation gases, as well as to throttle back the gas output.
A related concern involves the chemical composition of the gas stream supplied to the airbag. With certain gas generant formulations, undesirable quantities of carbon monoxide and/or nitrogen compounds (NOX) may be produced in relatively rapidly activating systems. The inflation gas is directed to the inflatable restraint device, and can ultimately end up in the passenger compartment of the vehicle. Because the proportions of these compounds can vary based on the response time and burn rate inside the inflator, attempts have been made to design inflator systems whereby a reduced amount of these gases is produced.